This invention relates generally to methods of and apparatus for producing booklets and the like, and is also concerned with booklets and the like when produced by these methods. The term xe2x80x9cbookletxe2x80x9d used hereinafter is intended to cover any set of folded sheets which are stitched or stapled along an axis, which are glued, or which are simply folded. The term xe2x80x9cbookletxe2x80x9d is therefore intended to include items such as brochures, pamphlets, manuals and the like.
Customarily, the folding of a set of up to perhaps 30 or so sheets in a stitcher/folder machine results in the finished product having a distinct bow adjacent to the spine. This means that the booklet tends to open out, giving it a less attractive appearance, and also making it more difficult to stack a number of such booklets for storage and transportation purposes because they will not lie xe2x80x9cflatxe2x80x9d. One cannot stack a large number of such booklets all with the spine on the same side, because the stack becomes lop-sided. One has to stack the booklets with some spines on one side and some on the other, in order to equalise the stack.
A number of different forms of apparatus are known which are concerned with improving the fold of a set of sheets, usually by the use of a creasing device. GB2031798A shows the use of xe2x80x9csmoothing armsxe2x80x9d which have surfaces which press against the spine of the book, but not in a sense to deform the spine. The purpose of the smoothing arms in GB2031798A is to smooth material accumulations around the stitching holes and to prevent the entry of glue through the stitching holes into the interior of the book.
It is an object of the present invention to provide methods of and apparatus for treating such booklets so that the sheets will lie flat after treatment.
It is a further object of the present invention to provide methods of and apparatus for treating such booklets in which the spine of the booklet is deformed so that the sheets will lie flat after treatment.
In accordance with the present invention there is provided a method of treating a booklet of sheets folded to create a curved spine which comprises the steps of fixedly holding the folded booklet adjacent to the spine to create a protruding portion, and passing a forming means along the length of the protruding portion with sufficient pressure to produce a flattening of the curvature of the spine.
Preferably, the forming means is a pressure roller which is caused to undergo one or more passes along the length of the spine.
The amount by which the spine of the booklet protrudes clear of means by which it is fixedly held is adjustable so that this dimension can be varied in dependence inter alia on the number of sheets in the booklet and the material of which the sheets are composed. The amount of protrusion is preferably from 0.5 mm to 1.75 mm.
In a preferred embodiment of the invention the booklet is held clamped by jaws, which may be ribbed to improve their grip, which engage the booklet adjacent to the spine.
Also in accordance with the present invention there is provided apparatus for treating a booklet of sheets folded to create a curved spine, which comprises clamping means arranged fixedly to hold a set of folded sheets of material with a portion of the spine protruding from the clamping means, and forming means displaceable along the length of the protruding portion to exert pressure against the spine sufficient to produce a flattening of the curvature of the spine.
Preferably, the forming means comprises a roller which is arranged to be able to make one or more passes along the length of the spine.
In a preferred embodiment the clamping means comprises a pair of jaws, possibly ribbed, which are arranged to grip the folded sheets adjacent to the spine.
Also in accordance with the invention there is provided a booklet comprising a plurality of sheets of material folded about an axis and having the spine of the booklet deformed to a flattened shape.